Staplers adapted to join living tissue are well known. The earliest known type of staplers for such use were designed to be reusable and included high quality castings and machined parts of easily cleanable and sterilizable materials such as stainless steel (see, for example, the staplers described in U.S. Pat. Nos. 3,643,851, 3,819,100 and 3,873,016). Such staplers typically are sterilized before each use in sterilizing equipment located at the facility (e.g., a hospital) in which they are used. The high cost of disassembling, cleaning and sterilizing such staplers before each use makes their use uneconomical where only a few staples are to be applied to a patient. Also the time needed for the sterilization procedure between successive uses of such staplers further restricts their use where a series of patients may each need the application of only a few staples, such as may occur in a hospital emergency room.
More recently introduced types of staplers for joining living tissue are designed to be disposable (see for example the staplers described in U.S. Pat. Nos. 4,109,844, 4,202,480 and 4,256,251). Such disposable staplers are made of relatively inexpensive parts such as plastic moldings and metal stampings that are sterilized during manufacturing and are packaged so that they remain sterilized until they are used. Such staplers are intended for use on only one patient, however. Thus, while due to the savings in cleaning and sterilization costs their use may be less expensive than that of reusable staplers where approximately the quantity of staples packaged in the stapler is to be used (e.g., 15 to 30 staples), and the use of different sterilized staplers precludes problems of waiting for a single stapler to be resterilized between usages; the use of such disposable staplers is still uneconomical where only a few staples (e.g., less than 10) are to be used in a patient.
Of the known prior art staplers of the above types, the one having a structure closest to the present invention appears to be the disposable type stapler described in U.S. Pat. No. 4,202,480. That stapler comprises an elongate body having a guide surface adjacent a front end of the body, and an anvil transversely centered at the front end projecting at a right angle to the guide surface. Means are provided for feeding staples onto the guide surface with points of the staples adjacent the front end of the body, and a ram is mounted on the body for movement from an open position to a closed position to cause the ram to bend a staple on the guide surface closed around the anvil. The ram can be manually moved by a pair of toggle joint linkages attached between a rear end of the body and the ram. The toggle joint linkages are opposed and project away from opposite sides of the body when the ram is in its retracted position so that pressing the toggle joint linkages toward each other in a direction transverse to the guideway will move the ram from its open to its closed position. An improved version of that stapler has been sold for over 12 months under the trademark "Precise" by Minnesota Mining and Manufacturing Company of St. Paul, Minn., and has been found to be an effective mechanism for applying staples. Like the other disposable staplers on the market, however, its mechanism is too complex to make the stapler economical to apply only a few staples.